Newbie question here... I have an early 86 with cast iron heads. I have done some modifications that will require a retune for the prom chip. The mods I have done are:

Edelbrock High-Flo Intake base, SLP runners, Plenum(all port matched)
New 22lb Bosch III injectors
Deleted Cold start
Deleted smog pump
Deleted egr
180 degree t-stat
adjustable fuel pressure regulator
Stamped steel oem type roller rockers 1.5:1

Everything else is stock. I am looking for someone to calibrate my chip for these modifications. I don't know if I need messing around with the fuel/advance tables or even if it would give me a little more hp or not. I have been told that I would have to get a custom burn because the baseline that would have to be used would have to come from an 89 vette because of the deleted cold start valve, but the timing advance table used for that application would be too aggressive as this baseline is intended for the L98 w/aluminum heads....as there is much more timing advance and the aluminum heads can disipate the additional heat created by the additional advance...where the cast iron heads that I have would act more like a heat sink and running much hotter than the engine should. I am hoping to get some good advice here so I can make a well informed decision here. I am also looking for some kind of cable that I can connect to my laptop so I can datalog and learn/see whats going on...
I have been told that many companies do this on an adapter, and was wondering why they dont reburn the original chip.
Thanks

 

Your stock chip should be able to handle the modifications you have made to your car. You would need to burn a new chip if you changed the cam.

Elimination of the cold start will just require a little more cranking. You could change the chip to inject a little more fuel when first starting, but I don't think that is necessary. I eliminated my cold start injector when I added the SR to my stock bottom end 1985. I cranked a few seconds longer when cold.

I was also running 1.5 & 1.6 RR on the original iron heads.

 

The cold start delete is a zero - look at how the thing actually works: the couple of seconds that it actually Sprays, if it sprays at all, doesn't make Any difference in cranking times or how the thing starts. I know - mine starts up just fine without the cold start valve, even down to Zero degrees - like this morning!

The AIR delete does effect the numbers that the O2 sensor is reading vs. what it's (the ECM) targeting/expecting to see, but this only really effects anything on coasting/low load, which is the only time the AIR should have been putting air into the exhaust manifolds anyhow. Nothing that matters or really needs to be corrected for.

Anyhow - the only things you might want to mess with in your tune/Prom would be the EGR settings (which really won't matter since the valve isn't there anyhow) and the Fan on/off numbers (to work better with your 180 'stat). With the OEM tune the fan isn't coming on until much higher than the 180° 'stat is opening at - this could/should be fixed.. You Could do this by swapping the relay/wires around so that the main fan is operated by the switch in the pass. side head (instead of the Aux fan) and change That switch to a 195° version.

Otherwise you haven't changed anything that would create a need for messing with the chip - you are OK with what you have. The manifold/runners are the only Possibible mods that Could need to be corrected for - and unless you also have the Rest of the breathing opened up (High flow MAF, larger TB, ported heads, more cam, headers, no cats/larger exhaust, etc.) you really aren't getting any gains in airflow anyhow..

Not to say that playing around with the advance (mostly) and fuel tables wouldn't gain you a bit, but it isn't something that you Need to do..

That said, the OEM '85 fuel table does have "issues" in the coast/idle and low load areas - tending to go rich (well - without the AIR, anyhow). You only Feel this in open loop (motor cold), once in closed loop the ECM compensates anyhow (see the BLM table) and it doesn't matter. Your manifold change may or may not help or worsen this - I really don't know but I doubt it's significant. It Can be fixed by editing the fuel/airflow tables, although like I said, it doesn't really Do anything for the way it runs in closed loop. It Does make you feel better about the thing, tho

If you are curious what Can be edited in the PROM do this: Download a copy of Tunercat and a copy of an '85 BIN file and Look at the stuff you can edit in the file. I'll bet you will be surprised first at how much is there, then Second at how little of it really Matters to how the car runs. It comes down to timing and air/fuel, the rest is "fluff".

Just like a carb - jetting. And timing. The basics..

 

Thanks a lot Ron. Yeah, I really didnt know what the ecm consequences would actually be for these "mods". I did away with the cold start after I sent it to Jon at FIC to see if it needed any maintenance because I just replaced all the other injectors....I thought it may be leaking because I have had an hickup in the idle around 1000rpm ever since I bought the car. Turns out that the coils were shot and the spring was busted leaving the thing inoperative(wouldnt leak either), and yes, my car to would start every time no problem. I am just **** about things operating the way they should an I hate seeing the check engine light come on.
I do have a copy of tunerpro rt, but as I am just learning, I wouldn't know what to look for in these bin files. Where could I get these files? Is the 86E just a carry over from 85? Thanks for the input.

 

Sorry - I missed the fact you had an '86, not an '85.
Still - the process is the same, and the Functional differences in the two models of ECM are actually rather minor.

They Are different tho. the '85 ECM (1226870, using a 2732 chip) was specific to that single model year. The '86-'88 ECM (1227165 with a 27C128 chip) is faster and one generation newer. There some differences in the PROM file, mostly taking advantage of the extra memory available on the chip I expect, but Most of what you can or would edit is the same, and works the same way. You Ought to be able to find a download for an '86 (-7165 ECM) BIN from the TunerPro site. If not look up the ThirdGen F-Body forum (the same Engine and electronics year for year in a Camaro as a 'Vette) - good source there.

Everything I have is '85 or I'd send you copies..

The Other option would be to check out the TunerCat site. That software is Not free, but you don't need to pay for the correct "mask" for the chip you are using. I Think there are bin files through there as well.

Another thought - if you are getting an SES then you DO have a problem - not necessarily anything to do with the PROM program however. What's the code(s)?

 

Well I dont have any codes because I haven't cranked it up yet. I am still waiting on my exhaust manifolds to get here. Got a set off ebay for .99 cause I was the only one who bid on them. I was just going to cut the air injection tubes off and weld them back myself, but then I got to thinking that if they ever cam back with inspections here, I would have my old set and al the smog pump junk to put back on. The general consensus from everyone I spoke with was that I needed to get the memcal reprogrammed. The ecm I use is 16198259. I dont know what the chip # was as I sent it out yesterday.
I have an odd year. They introduced aluminum heads that year and there was a problem with the heads cracking, so they used cast iron heads until they could get the problem fixed(mid 1986). I am sure the timing and fuel tables are different for this during that year. I dont know if Camaro is like this. I also didnt know that even if the electronics were the same, I dont know if the tunes were the same.ie..fuel pressure, injectors, rear end ratios, advance, so on. I am still learning. It's only costing $60 for the retune(if it works properly). I needed a starting point, looking for a cable to connect to my laptop so I can undersand in real time whats going on.

 

Are you Sure that ECM # is right? That number ought to be '94-95 time frame, it Certainly isn't anything that would work in an '86 vehicle.

The reference list I looked at didn't Have that exact number, but the 1619XXXX ECM numbers all date at that much newer than what the car ought to have...

As for the alloy vs. steel head deal.. The late model year (finally) intro of the alloy head castings meant that very few coupes got alloy heads and All of the 'verts Did get them. There is essentially No difference between the heads, slight Port variations and therefore a Very slight improvement in breathing. Same compression, valves, combustion chamber shape, etc. Nothing Else in the motor was different either - same cam, pistons etc. Same bin files too in the chip - nothing is iron head or alloy head specific or different. I say that without personal intimate knowledge of the '86 files - but I haven't Heard of anything different.

The Biggest advantage of those old GM OEM alloy heads was the 5-6 lb. apiece that they were Lighter than the iron heads..

Just like there really isn't anything in the .bin files (that can't be dealt with) to differentiate between an Automatic car and one with a standard shift. Really it's just the TC lockup stuff, not used in a 4+3 car, obviously. Still there in the .bin tho, waiting.

Matter of fact - I use the almost exactly the same .bin file in my auto trans Vette as I do in an old '78 4wd Pickup truck, with a simple 350 in it and a granny gear Four speed. Yes, an '85 vintage TPI setup - same stuff as in my 'vette. Everything interchanges that way..

 

I am looking at it right now. That's what the service # is. It's been working well in mine other than a little miss around 1000rpm. Hasnt set any codes. But then again, this thing was a basket case when I got it. been putting it back together for the better part of a year now. But I do know the block matches the vin#, but according to this page,http://www.motorera.com/corvette/1980/vet86.htm
my car originally came with a manual..code DKC. But as far as the ecm goes, I havent had any issues with it. It's a delco reman. I dont know, where did you get your references from?
I do know that the three tuners I spoke with said the advance tables for the aluminum headed engine had a higher total advance at around 48 degrees. They told me it was more than the engines that came with iron heads and that GM did this because the aluminum heads could disipate the extra heat more easily.



http://tpiparts.net/ecms_and_proms/

1986-1989 - 1227165 ECM - Camaros, Firebirds, and Corvettes

"This is the most common ECM which is used on MAF style setups. ECM number 16198259 is equivalent and can be used in its place without any problems. The same computer was used both for 305 and for 350 engines. The only difference between the two engine sizes was the PROM that was used. The Mass Air Burnoff Module that GM used in 1985 is no longer present. This model is part of the P4 ECM family. This ECM can be easily recognized by having the PROM access cover in the center of the unit, and has only two harness connectors.

Support for this ECM with regards to PROMs is much more common. Due to the nature of the MAF sensor, it is very easy to run a large or moderate cam without needing PROM changes. This system is not very sensitive to engine changes, and can adapt fairly well. However, many enthusiasts find that it is a little more difficult to fine tune than the later Speed Density system. Please realize that this is a matter of opinion and personal preference. Each of these systems have advantages and disadvantages over one another. ALDL data is sent at 8192 baud, much faster than the 1985 ECM. This allows for several sets of data per second."

 

OK, Found it.

http://www.cruzers.com/~ludis/p4xref.html#16198259

Looks like I didn't know that the 16198259 (which is a much more recent number) is, in fact, a replacement for and equivalent to the 1227165. Had me wondering there, for a bit..

The Alloy head '86 .bin may, in fact, have a bit more Total advance than the Iron head version, but it's meaningless. The only place you'll see those numbers is in the upper RPM/No load area of the map (the three dimensional "surface" representing the data table. Advance is plotted on the Z axis above the RPM and Load on the X and Y). The OEM advance map is weird anyhow - there are strange "valleys" in there, my guess is to work around what happens when the EGR is supposed to be opening/closing, which would effect the combustion temps and therefore require or allow advance changes. (no EGR means higher combustion temps and more liklihood of pre-ignition. Also means increase in NOx emissions for the same reason, but that's a different discussion)

In reality the alloy heads have the same compression and the same combustion chamber shape as Iron heads. Same Cam in the motor. Not enough difference in the two motors to say so - Going to want/need pretty much the same advance map. Yes, alloy heads (in general) cool better, but These alloy castings are NOT significantly different in design from the Iron heads that they were patterned after - any improvement in knock control from better combustion chamber "hot spot" reduction is Really minor.. And you are running a 180° 'stat anyhow instead of the factory 210°. The whole discussion goes out the window.

GM did a Much better job a couple of years later with the cooling passage design in the Vortec heads (in Iron) and was therefore able to bump the compression ratios up significantly - leading to a nice increase in HP/torque. And from there to the LTx and LSx motors, and etc..

The ability to control and reduce detonation is entirely dependant upon combustion chamber shape and elimination of "hot spots" in that chamber. Better detonation control in turn means being able to increase static compression ratios. The amount of spark advance needed is, in Theory, completely determined by the flame speeds within the combustion chambers and by the engine rpm. And the chemical/physical properties of the Fuel mixture.

In Reality the amount of spark advance Usually has to be reduced from what would be ideal because of detonation - particularly under elevated loads where the cooling capacity around the exhaust valve and spark plug areas of the head (or whatever other "hot spots" may exist) isn't sufficient to prevent the material temps from rising and triggering pre-ignition.

Better cooling design (along with combustion chamber and port designs which maintain turbulence and even mixing in the chamber) is the key here which allows for spark advance that more closely matches the theoretical ideal, and for static compression ratios to increase. All of which makes for increases in Torque and makes all of us gear heads Happy

Damn - must be early, I'm running on. Time for more coffee..

Oh - I should add.. I personally Like the 1226870 in the '85. It uses a stand alone MAF control module, much more reliable than the two relay method of the 1227165. It Also uses a "bare" PROM chip, the single chip by itself in a socket. Simpler, easier and less expensive to mess with. The only down side I see for the 1226870 is that the ALDL output is at a much slower baud rate, making "real time" scanning a bit more cumbersome. All this stuff is 30 year old tech - a Long way from "cutting edge" these days...

 

Thats ok, I am on my second cup...trying to warm up. It's 30 outside. I know its probably pretty cold where your at, but jeez, I'm in Florida!

Thanks for all the good info!
Skip

 

30! Must be nice, I had -8 at the house when I left at 5:00.

It's OK tho, I'll be down There in a couple of weeks - the annual Speed week trip. I used to live in St. Pete, Mom is still there, and the annual trip for the racing in February is usually one of a couple trips down every year...